If you are trying to get the barrel to cycle target ammo, then you need to gradually enlarge the hole, one drill bit size at a time, until the gun works. It will no longer be able to shoot high powered shells without causing damage to the gun. Mark

Why wouldn't you just buy a used target barrel with the two ports for short money. You could be creating a real problem for someone down the road who ends up with the altered barrel and is not aware of the changes made. Please, think through what you're contemplating. Good luck and shoot safely.

My 1100 Mag (early 70's, unaltered, bought new) has always cycled target loads with no problem. If you make the hole larger be sure to take small steps and try it. The best solution was given above: BUY ANOTHER BARREL FOR TARGETS. They are not expensive. Marc